← ⚛️ Physics · usually met in Std 6-10
The force that resists sliding — the reason walking works, brakes work, and machines get hot.
Two surfaces touching are never as smooth as they look. Magnified enough, both are ranges of hills, and sliding one over the other means dragging those hills across each other. That resistance is friction, and it always acts against the direction of movement.
It is easy to think of friction as the enemy, because it wastes energy as heat and wears parts out. But nothing would work without it. You walk by pushing backwards on the ground and letting friction push you forwards; on wet marble that bargain fails and you fall. A nail holds a plank by friction. A knot holds by friction. Engineers do not try to remove friction, they decide where they want it — grip here, oil there.
Want to see it moving? Search YouTube for “Friction” ↗ — we send you to the search rather than to one video, because a link to one video eventually rots.
This entry was written for Star Student in our own words — it is a summary, not a source. Here is where the people who actually hold these facts keep them. Go and check.
Your own textbook ↗Balbharati publishes the textbooks free to read online. Your chapter is the thing to check first — an encyclopedia is a summary, and the syllabus is the syllabus.Last gone through: 1 October 2026 · How these entries are written
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